A convenient synthesis of organophosphorus analogs of β-phenylalanine containing functionalized 2-phenylethylphosphonous and 2-phenylethylphosphinic acid moieties has been developed. The radical addition of bis(trimethylsiloxy)phosphine to styrene, trimethylsilyl cinnamate, or arylacetylenes proceeds regioselectively to give a variety of substituted 2-phenylethylphosphonites, and the subsequent functionalization